Improvement in door-bolts



UNITED STATES PATENT OFFICE.

ADOLPH Gr. HOFSTATTER, OF NEW YORK, N. Y.

IMPROVEMENT IN DOOR-BOLTS.

Specification forming part of Letters Patent No. 137,841, dated April 15, 1873 application filed March 8, 1873.

To all whom it may concern.-

Be it known that I, ADOLPH G. HOFSTAT- TER, of the city, county, and State of New York, have invented a new and useful Improvement in Looking Attachment for Slide- Bolts, of which the following is a specification Figure l is a face view of an ordinary bolt to which my improvement has been applied. Fig. 2 is a detail cross-section of the same taken through the line m at, Fig. 1.

My invention has for its object to furnish an improved attachment for bolts, by the use of which it will be impossible for the bolt to be worked back and the door unfastened from the outside of said door, and which shall be simple in construction, inexpensive in manufaeture, convenient in use, readily applied, and effective in operation. The invention consists in the semi-cylindrical plate in combination with the plate, the bolts, and the keeper of an ordinary slide-bolt, as hereinafter fully described.

A represents. the plate; B, the bolt; (3, the closed or end keepers; and D, the open or central keeper, through which the knob of the bolt passes in operating the bolt to fasten and unfasten the door. E is a semi-cylindrical plate, which is placed upon the bolt B within the open keeper D, and at the rear of the knob of said bolt B. The plate E is made of such a width that it cannot come out through the slot of said keeper D.

By this construction, when the bolt is pushed outward so as to bring the knob of said bolt into the space between the forward end of the open central keeper D and the rear end of the forward keeper 0, and the plate E has been moved laterally upon the bolt B so as to cover the opening or slot in the central keeper D, it will be impossible for the bolt to be drawn back without first moving the plate E to one side to uncover the said slot and allow the knob of the bolt B to pass back through it.

Upon the rear end of the plate E is formed a small projection, E, which, when the said plate is adjusted to cover the opening in the keeper D, may be slipped into a notch in the forward end of the rear keeper 0, and which, when the said plate is moved to uncover the said opening, may be slipped into a notch in the rear end of the open keeper D, to prevent the said plate from getting out of place accidentally when in either position.

Having thus described my invention, llclaiin as new and desire to secure by Letters Patent The semi-cylindrical plate E in combination with the plate A, bolt B, and keepers G D, of an ordinary slide-bolt, substantially as herein shown and described, and for the purpose set forth.

ADOLPH G; HOFSTATTER.

Witnesses JAMES T. GRAHAM, T. B. MOSHER. 

